Metal vapor-jet pump



J. M. VAN DER PoEL METAL VAPOR JET PUMP Filed NOV. ll, 1924 Patented May 14, 1929.n

UNITED STATES PATENT OFFICE.

JOHANNES MARINUS VAN DER POEL, F EINDHOVEN, NETHERLANDS, ASSIGNOR T0 N. V. PHILIPS GLOEILAMPENFABRIEKEN, 0F EINDHOVEN, NETHERLANDS.

METAL VAPOR-JET PUMP.

Application tiled-November 11, 1924, Serial No. 749,357, and in the Netherlands May 8, 1924.

This invention relates to metal vapor jet pumps, more particularly to mercury vapor jet pumps but may also be applied for eX ample to pumps operating with the vapor of metals that have at ordinary temperatures a lower vapor pressure than mercury, such as lead, tin, bismuth, cadmium, zinc and the like. p

Metal vapor jet pumps are hereinafter to be understood'to mean pumps that are constructed in such a manner that they are capable of operating against a comparatively poorI prcvacuum; for example, a pressure of mm. or more.

It has already been proposed to construct mercury vapor jet pumps that have several stages. As" arule these pumps are provided with a central 'jet tube of circular section and with one or more annular jet tubes, whilst the mercury vapor between two successive stages is condensed by cooling.

In such pumps the good operation depends on the ratio of the vapor speeds in the several. stages and itis therefore necessary that the once determined surfaces of the sections of the jet tubes be constantly maintained in the course of time, asotherwise the pump loses its good effect. In practice it occurs that the size of the section of the jet tube is modified, owing to the precipitation of some substance or other on the walls of the jet tube near the outlet aperture and especially on the wall of the cooling vessel. This occurs, for example, in exhausting electric vacuum lamps, the filaments of which are frequently sprayed with red phosphorus. During the exhaustion a little phosphorus vapor is carried along and phosphorus is precipitated in the pump, especially in the said places. The operation of the pump diminishes and may even entirely cease.

Besides in pumps haviner several stages, the said inconvenience may a so present itself in pumps that operate with only one vapor jet.

The object oi. the invention is to construct metal vapor jet pumps, more particularly mercury vapor jet pumps adapted to the exhaustion of electric incandescent lamps and the like, in such a manner that the pump can easily be taken to pieces so that it is possible to cleanits members, especially the jet tubes. Such a construction is possible if according to the invention in singleor the hoods that the latter can be removed in I upward direction. According to the invention the cleaning of the pump may be facilt tated still more by constructing the pump so as to allow the removal of the central vapor supply tube with the jet tubes pertaining to it without further necessity of taking the pump to pieces.

According to the invention the vapor supply from the central vapor supply tube to the successive jet tubes can be reUulat/ed by means of apertures provided in t e wall of the central tube. The apertures for the vapor supply to the jet tube (tubes), lying on the high vacuum side of the pump, have preferably a regulable size.

According to another characteristic'of the invention, the mercury vapor jet pumps may be so constructed that they, after havingbeen. filled with a gas of high pressure, can rapidly be put into service again without any risk of mercury flowing out of the pump.

Mercury vapor jet pumps can operate against a comparatively poor prevacuum of, for example, 20430 millimeters and the pumps that have several stages, are able to `reach a very high vacuum. Such pumps have the inconvenience that if for some reason or other, for example owing to a leak in the high vacuum conduit, the pumphas been filled with gas of high pressure and it is then put into service again, mercury is thrown out. This is caused by the sudden boiling up of the mercury when the gas pressure in the pump is suddenly reduced, after the latter has been filled with a gas of high pressure. An excessively large quantity of mercury vapor is formed and, moreover, mercury from the receptacle is carried along with it so that, ii' there is not a sutiicientspace for condensation the mercury vapor flows into the prevacuum conduit; it may also occur that the prevacuum conduit gets clogged by .that consequently chamber, -w ich enables the mercury thatv isy lcondensed 'and-eventuallycarried along, to

be collected' and tothe 'upper surface of which the vapor jet chamber `'and the; pre-- vacuum conduit are led `,may be arran ed arcund the central vaporsupply tube# ccording to the invention that portion of the `prevacuum conduit that is connectedl to the pump, maybe .helically wound andbearl 1 ranged within f way. of Aexamp lvfthe" cooling vessel of the;

'pumps according to the invention, thathave two f annular jetv tubes arranged.` one.' Latter lthe other; f

Figure "1 'is 'a mercury -vapor jet pum iaccordlngto the Y invention, provided'fwit Ltwo annular `.jet

tubes anda mercury vapor jet'pum `according tothe invention, likewise provi edwithtwo annular jettubes and a removable supplyf .tube, in

Y. g Thepurnp shown in Figure 1 is provided vly wound prevacuum conduit arearranged.'

The, l maybe who v ever,-that the invention can also be applied pum s according to. the invention of metal; it is observed, howyof to pumps consisting wholly or partia f witha mercury receptacle 1 from which a central `vapor supply tube 2 rises up. A quantity ofmercury 3 in the receptacle 1 may be heated in any suitable manner for example, electrically or with the aid of gas burners. The mercury `vapor produced moves upwards through the tube 2 and divides over annular jet tubes 4 and 5. The jet tube 4 is formed by the outer wall of the tube -2 and a wall 6, which forms plart of a hood 7, which rests on an edge 8. he supply of vmercury vapor to the jet tube 4 is'.

regulated by a number of apertures 9 in the wall of the tube 2.

The annular jet tube 5 is formed by the 4outer wall of the hood 7 and the inner wall of a hood 10, which rests on the upper endit e hood 7. As the hood 7 is rotatable in the tube l2, the size of the apertures for the vapor suppl to the jet tube 5 may be regulated at The vapor jets coming from the jet tubes i d recipitation 'of phosphorus'carrie The accompanying drawing illustrates, iby.f': some constructions;4 of* longitudinal l section oi a 5 and 4, carry along with them the of a'fchamber 15 and condense then on te wall 'o'f a veel 16, which is cooledby means of xa' circulating coo 'ng liquid, lowing through a cooling vessel 1 provided with su lyand discharge conduits 18 and 19.

densed mercury llows back through a tube 2O into the receptacle l1, `whilst the gases carried along by the mercury vapor, are dischar by meansv of a prevacuum conduit 21. e vessel to be exhausted is connected to the upperend of the tube 16.

If forr some'reason, however, the pump has become soiled, forA example, owin t3 the rom incandescent lamps, near the outlet o the vjet tubes 4 and 5, the pump can be easily cleaned by removing the supp y tube 2 with thehoods 7 and 10. r

The pump `illustrated in Figure 2 operates with two annular jet tubes arranged one after the other and may be made entirely of metal.

.A receptacle 31, containin a quantity of mercury 32, is rovided wit a cylindrical `chamber 33, wit in which a heating device, for example an electric heating resistance `can be placed. From the receptacle 31, 'which is surrounded by a heat insulatin jacket 34, the mercury vapor flows throng y a common cylindrical vapor sup ly tube 35. At the up r end of this tube t e mercury va or is ivided over annular jet tubes 36 'an 37` to which apertures 88 and 39 in the wall ofthe tube give access. The jet tube 36 is formed by the outer wall of the tube 35 and a wall 40 pertaining to a hood 41 which is slid on the upper end of the tube 35 and rests on the edge 42.

The annular jet tube 37 is formed by the outer wall of the hood 41 and the inner wall of a hood 43, which by means of a screw 44 is connected to a cover 45 of the tube 35.

Around thejet tubes a jacket 46 is nrranged, which iscooled by means of a cooling iquid circulating through a cooling vessel 47 with supplyand discharge conduits 48 and 49. v

The high vacuum conduit is connected to the upper end. of a jacket 46 whilst a prevacuum conduit 50 passes into a helically wound portion 51, which leads to the top of an annular chamber 52. The vapor jet chamber, also, is opened out into the-u per surface of the said annular chamber, w ereas in the bottom of the said chamber conduits 53 and 54 end, which serve to return the condensed mercury to the receptacle 31.

The operation of the pump shown in Figure 2 is similar to that of the pump illustrated in Figure 1. In the normal operation ofthe pump the mercury vapor condenses substantiall entirely on the wall of the tube 46. 1% however, for some reason or other, for example, owing to a leak in the ev conhighvacuum conduit or to the ,communica-4 tioriof` the highvacuum conduit with a vessel containing air under atmospheric pres sure;y gas of ja' `,high pressure has tlown into the pump andj'if then thepressure in the pumpk issuddenly reduced owing to the' suckingaWay-of gases by ,the revacuuni p Iconduit, an a normally highdeve opment oi .inercuryvapor will be producedin the manner' alreadydescribed, so` that only art of j `the `mercuryfvapor can .condense on t "ev wall ff'yof the tube 46, fora considerable part Showever, also flows into the helically wound por- "tion' 51 of the prevacuum conduit. llhisvih` -poricondenses and flows together with any .mercury carried alon `b the vapor, back intothe chamber 52, w ic is large enough to containthe considerable quantity of mer;

" cury that is formedand whence the 'mercury can flow back intothe Vreceptacle 31.# No

.mercury is, therefore, thrown out/andthe, pump according to the invention odors,

moreover, the advantage that it, after hav-f ing been filled with a gas of highfpressure,

that every time a considerable quantity of air flows into the ump.'-

' The pump according to the invention may be so constructed that .it is capable of operating against a comparatively bad prevacuum of, for example, 20 millimetres, whereas on the other hand it is capable of reaching -a very good vacuum, for example, as is usual in high vacuum discharge tubes for wireless telegraphy. The pump may operate in scries with an other high vacuuin pump. which ensures therefore a very good prevacuum.

lVhat I claim is: t 1. A metal vapor jet pump comprising a boiler, a tube communicating with said boiler, at least two removable hoods arranged around said tube and forming downwardly directed annular converging jet tubes, a condensing chamber surrounding said hoods, a cooling system for cooling said condensing chamber, a connection from a vessel being y evacuated to said condensing chamber and a -pre-vacuum conduit from said condensing chamber to a vessel in which a'low pressure is. maintained.

2. A metal vapor jet pump comprising a boiler, a tube communicating with said boiler, at least two removable hoods arranged around said tube and forming downwardly directed annular jet tubes, the inner walls of said tube being non-diverging, a condensing chamber surrounding said hoods being so constructed that the hoods can be removed in upward direction, a cooling system tor cooling said` condensing'cbamher, a comicol tion from` a vessel bem evacuated to said condensing chamber an a pre-vacuum con- I.

duit from vsaid condensing chamber. to a'v vessel in which a low pressure is maintained. 3; A metal vapor Jet pump comprising a 4 boiler, a tube communicating with said boil er, at least two removable hoods arranged* around said tube and forming annular jet tubes, said tube' and said removable hoods being adapted to be removed from the ump without further necessity to take the atter ,to pieces, a condensing chamber surrounding said hoods closely, a coolin system for cooling said condens1ng-cham r, a connection from the vesselto' be evacuated to said condensing chamber and a prevacuum conduit `from said condensing chamber to a vessel in' which a low pressure is maintained.

.4. A metal vapor jet pump comprising 'a boiler, a tube communicating with said boiler and resting on the upper end-of said boilc er, a plurality of removable hoods arran ed around said tube and forming downwar ly ydirected annular jetltubes with non-diverg ing wells, a condensing chamber surroundg ing said hoods and bein .so constructed that the hoods `together wit said tube can be removed in upward direction, a coolin sys- `tem for cooling said condensing cham r, a

connection from a vessel being evacuated to said condensing chamber, a re-vacuum cony duit from said condensing c iamber to a vessel in which a low pressure is maintained and a drain passage from said condensing chamber to said boiler.

5. A. metal vapor jet Apump comprising a boiler, a central supply tube communicating with said boiler, at least two removable hoods arranged around said tube and forming downwardly directed annular .jet tubes, apertures in said central supply tube adapt ed to regulate the stream of metal vapor through said annular jet tubes, a condensing chamber surrounding said tubes closely:l a cooling system for cooling said condensing chamber, a connection from the vessel being evacuated to said condensing chamber and a pre-vacuum conduitfrom said condensing chamber to a vessel in which a low pressure is maintained. I

6. A metal vapor jet pump comprising a boiler, a central supply tube communicating with said boiler, at least two removable hoods arranged around said tube and forming downwardly directed annular jet tubes, apertures in the wall of said 4supply tube adapted to regulate the stream of` metal vapor through said jet tubes, the apertures lying on the high vacuum side of the pump having a regulable size, a condensing chamber surrounding said hoods and so constructed that the hoods together with said suppl tube can be removed, a cooling system or cooling said condensing chamber,

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a connection from the vessel being evacuated to said condensing chamber, a pre-vacuum conduit from said condensing chamber to a vessel in which a low pressure is maintained and a drain passage from saidcondensing chamber to said boiler.

7. A metal vapor jet pump comprising a boiler, a tube colnmunicating with said boiler, at least two removable hoods arranged around said tube and forming downwardly directed annular jet tubes, a condensing chamber surrounding said hoods closely, a cooling system for cooling said condensing chamber, a connection from the vessel being evacuated to said condensing chamber, said connection being so constructed that the hoods and the central su ply tube can be removed without taking the pump to pieces and a pre-vacuum conduit from said condensing chamber to a. vessel in which a low pressure is maintained.

8. A metal vapor jet pump comprising a boiler, a tube communicating with said boiler, at least two removable hoods arranged around said tubc and forming downwardly directed annular jet tubes, a condensing chamber surroundingr said tubes, a

.cooling system for cooling said condensing chamber, a connection from a vessel being evacuated to said condensing chamber, a pre-vacuum conduit from said condensing chamber to a vessel in which a low pressure is maintained, said pre-vacuum conduit being helically Wound and enclosed by said cooling system and a drain passage from said condensing chamber to said boiler.

9. A metal vapor jet pump comprising a boiler, a tube communicating with said boiler, one or more removable hoods arranged around said tube and forming downwardly directed annular jet tubes, a condensing chamber surrounding said hoods, a cooling system for cooling said condensing chamber, an annular chamber arranged around said tube and adapted to collect the condensed mercury, a connection from a vessel being evacuated to said condensing chamber, a pre-vacuum conduit from said condensing chamber to a vessel in which a low pressure is maintained, said pre-vacuum conduit entering the pump in the top of said annular chamber, and a drain passage from said annular chamber to said boiler.

10. A metal vapor jet pump com risn a boiler, a tube communicating witl sai boiler, one or more removable hoods arranged around said tube and forming downwardly directed annular jet tubes, a condensing chamber surrounding said hoods and so constructed that the hoods, together with said tube, can be removed from the pump without further necessity to take the latter to pieces, a cooling system for cooling said condensing chamber, a connection from a vessel being evacuated to said con densing chamber, and a pre-vacuum conduit from said condensing chamber to a vessel in which a low ressure is maintained, said conduit bein heIlicaIly wound and enclosed within sai cooling system.

11. A metal vapor jet pump comprising a boiler, a central supply tube communicating with said boiler, one or more removable hoods arranged around said tube and forming downwardly directed annular jet tubes, apertures in the wall of said supply tube adapted to regulate the stream of metal vapor through said jet tubes, the apertures lying at the high vacuum side of the pump havinga regulable size, afcondensing chamber surrounding said hoods and being so constructed that the hoods, together with said supply tube` can be removed, a cooling system for cooling 'said condensing chamber, an annular chamber arranged around said supply tube and being in open communication with said condensing chainber and adapted to collect the condensed mercury, a pre-vacuum conduit from said annular chamber to a vessel in which a low pressure is maintained, said pre-vacuum conduit being helically wound and enclosed Within said cooling system, and a drain passage from said annular chamber to said boiler.

In testimony whereof I aflix my signature, at the city of Eindhoven this 22nd day of October, 1924.

JOHANNES MARINUS van der IOEL. 

